Transcript Disorders
The Human Genome HUMAN GENETICS Dominant and Recessive Homozygous/Heterozygous work for human genes too! REMEMBER YOUR MOLECULES! Proteins are made by joining ________ amino acid ___________ subunits together REMEMBER YOUR MOLECULES Genetic code is carried __________ sequence of in the ________ A, T, G, C’s on a DNA molecule _____ The sequence of A’s, T’s, G’s & C’s ORDER of amino acids in tells the _______ ________ the ________ protein Changes in the gene code _______________ change the protein that is made A change in the genetic code = MUTATION ________________ KINDS OF MUTATIONS SOMATIC CELLS BODY ________ CELLS = ___________ Somatic cell mutations can: ______________________ Cause cancer Make cell not able to function ______________________ _____________ Kill cell WON’T BE passed on to offspring BUT _________ Kinds of Mutations GAMETES ___________ (sperm & eggs) GERM = _________cells CAN BE passed Germ cell mutations ________ on to offspring http://anthro.palomar.edu/biobasis/images/meiosis.gif MUTATIONS can be: ____________Most mutations have little NEUTRAL function or no effect on gene ____________. REDUNDANCY in _____________ code can absorb many mutations without changing the amino acid sequence. UUC and UUU both code for same amino acid MUTATIONS can be: ____________ HARMFUL - Mutations that produce defective proteins are usually harmful. ______________ Harmful mutations are associated with many genetic disorders and can cause ________________ ____________ cancer MUTATIONS can be: ____________ - Some mutations LETHAL change proteins that are so vital to life that they cause death, usually before birth. 50% of pregnancies that abort spontaneously have genetic abnormalities http://www.global-warming-and-the-climate.com/images/tombstone-RIP.gif MUTATIONS can be: BENEFICIAL ____________Mutations are also a genetic variation source of ______________ in the population Mutations can help an organism survive and reproduce _________________ Provide a way for species to change over time MORE ON THIS in 2 weeks REMEMBER! _______________ MUTATIONS are changes in the genetic material. Mutations can happen: mistakes in copying DNA • when cells make_________ • when cells are exposed to environmental carcinogens like ___________ radiation __________X-rays, tanning booths chemicals - cigarette smoke, pollutants __________ viruses __________ - HPV Images from: http://www.bbc.co.uk/scotland/education/bitesize/higher/img/biology/genetics_adaptation/mutations/02gene_mutation.gif KINDS OF MUTATIONS Mutations that produce changes in a single gene = GENE MUTATIONS _________________ Mutations that produce changes in whole chromosomes = CHROMOSOMAL MUTATIONS _____________________ A mutation that causes a protein to be NON-FUNCTIONAL would appear RECESSIVE _______________ to the normal working allele. AUTOSOMAL RECESSIVE Examples of __________________________ GENETIC DISORDERS: PHENYLKETONURIA (PKU) ____________________ TAY-SACHS DISEASE ____________________ CYSTIC FIBROSIS ____________________ Phenylketonuria (PKU) CAUSE: ENZYME Mutation in gene for an ___________ that __________ called breaks down an ___________ amino acid phenylalanine X X MENTAL RETARDATION Build up causes ________________________ http://biology.clc.uc.edu/courses/bio104/protein.htm Phenylketonuria (PKU) ALL babies are ________ tested ____ for PKU before they leave the hospital. http://labspace.open.ac.uk/file.php/2588/SK195_6_002i.jpg Treatment: LOW in phenylalanine to Need a diet _____________________ extend life and ______________ mental PREVENT retardation amino acid If phenylalanine is an _____________, what type of foods should PKU patients avoid? PROTEINS ! __________________ THINK ABOUT IT What does a can of Diet Coke have to do with human genetics? LOOK AT THE WARNING LABEL ! NUTRASWEET is made with phenylalanine ______________ TAY-SACHS DISEASE AUTOSOMAL RECESSIVE ___________________ CAUSE: Mutation in gene for an ___________ ENZYME that breaks down a kind of _________in the LIPID developing _________ BRAIN Build up of lipids in brain cells leads to: mental retardation, blindness, and DEATH in early childhood Found more frequently in people with Jewish _____________ Mediterranean ______________, Middle Eastern _______ ancestry Image from: http://www.djsfoundation.org/images/Steeler%20pics%20Dylan.jpg CYSTIC FIBROSIS CAUSE: Loss of 3 DNA bases in a gene for the _____________ that transports _________ so protein Cl- ions salt balance is upset thick mucous Causes a build up of _________________ in lungs and digestive organs Image from: BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006 REMEMBER TRANSPORT ION CHANNELS are membrane _____________ proteins that make _________ tunnels through the bilayer for ____ ions to pass through (Na+, K+, Ca++, Cl-) CYSTIC FIBROSIS http://learn.genetics.utah.edu/content/disorders/whataregd/cf/index.html CYSTIC FIBROSIS Leads to: _________ and _________ respiratory digestive complications, increased susceptibility to infections; Salty skin is a symptom “__________” Caucasians More common in ____________ but can affect all races. 30,000 people in U.S. have cystic fibrosis 1 in 31 people are carriers A mutation that codes for a new protein whose action masks the normal allele appears as a ______________ DOMINANT mutation. AUTOSOMAL DOMINANT Examples of _________________________ GENETIC DISORDERS: Huntington’s disease ____________________ Achondroplasia ____________________ HUNTINGTON’S DISEASE AUTOSOMAL DOMINANT ______________________ CAUSE: CAG repeats at end of gene Extra 40-100 ______________ on chromosome 4 more repeats . . . the more __________ severe The _____________ the symptoms. http://www.healthsystem.virginia.edu/internet/huntdisease/images/cag.gif HUNTINGTON’S DISEASE Huntington’s brain loss Causes progressive _____ muscle control of ________________ and mental ___________function 1 in 10,000 people in U.S. have Huntington’s disease Normal brain http://www.scielo.br/img/revistas/bjmbr/v39n8/html/6233i01.htm A person with Huntington’s disease 50% chance of has a _____ passing the disorder on to their offspring. Problem: Symptoms of disorder usually don’t show until ____________ MIDDLE AGE . . . so you don’t know you have it until ________ AFTER you have had children. THINK ABOUT IT Click to hear Woody’s song What does the song have to do with human genetics? “This Land is My Land” was written by a musician named Woody Guthrie before he began to show the symptoms of Huntington’s disease. Woody Guthrie had a son named Arlo that was a popular musician during the 70’s Click to hear one of Arlo’s songs Before 1993 there was no test for Huntington’s. If one of your parents showed symptoms, you had to wait to see if it had been passed on to you. http://www.jimdirden.com/woodyfest2004/artists/index_3.htm Arlo Guthrie is still performing today. He never developed symptoms for Huntington’s disease. If there is no cure, would YOU want to be tested and find out if you have the gene? http://webs.wichita.edu/depttools/depttoolsmemberfiles/accomp/question_mark%20(WinCE).jpg ACHONDROPLASIA (One kind of Dwarfism) AUTOSOMAL DOMINANT CAUSE: ___________________________ gene 1 in 20,000 births 200,000 “little people” worldwide One of oldest known disorders – seen in Egyptian art ACHONDROPLASIA (One kind of Dwarfism) Normal size head and torso; short arms and legs Problem with way cartilage changes to bone as bones grow DISORDERS CAUSED AUTOSOMAL Recessive ALLELES BY ____________________ SICKLE CELL DISEASE ____________________ CAUSE: T changed to A in gene for HEMOGLOBIN __________________ (protein in red blood cells that carries oxygen in blood) SICKLE CELL DISEASE Play SYMPTOMS: RED BLOOD CELLS become sickle _____________ TWO shaped in persons with ______ ALLELES sickle cell ________ SICKLE CELL DISEASE Circulatory problems Cells stick in capillaries Loss of blood cells (anemia) Organ damage (brain, heart, spleen) Can lead to DEATH SICKLE CELL DISEASE AFRICAN AMERICANS More common in _________________ 1 in 500 = have sickle cell disease 1 in 10 = carriers for allele MEDITERRANEAN Also affects persons of _______________ and _________________ MIDDLE EASTERN descent Why do so many African Americans carry the sickle cell allele? SICKLE CELL DISEASE Many can trace their ancestry to west MALARIA central Africa where ___________, a serious parasitic disease that infects red blood cells is common. Watch a video about sickle cell and malaria Images from: http://en.wikipedia.org/wiki/Malaria A person who is __________________ for HOMOZYGOUS the ____________allele (ss) will have sickle cell _______________ sickle disease HOMOZYGOUS A person who is _________________ for normal hemoglobin alleles will have normal blood cells, but can become infected with malaria __________ (SS) HETEROZYGOUS person (Ss) A _________________ (with one normal/one sickle cell allele) is generally healthy and has the benefit of resistant to malaria being _________ KARYOTYPE is a picture of A __________ an organism’s chromosomes Chromosomes that determine the sex of an organism = _________________ Sex chromosomes http://www.angelbabygifts.com/ All other chromosomes = _________________ autosomes Humans have two sex chromosomes X y and _____ 44 autosomes SEX DETERMINATION XX = female Xy = male SEX CHROMOSOMES CAN CARRY OTHER GENES TOO = ___________________ SEX LINKED TRAITS These traits show up in different _______________ in males and females percentages because they move with the sex chromosomes Y-LINKED GENES: carried on Y Genes ______________ chromosome EXAMPLE: Hairy pinna ONLY show up _______ in males Y linked _________genes _____ X-LINKED GENES: ____________ are carried on the X chromosome X-linked recessive disorders MORE frequently show up _____________ in MALES ______ than females because males only have ONE X chromosome. ______ Males ONLY HAVE ONE X DEFECTIVE They either have the disorder NORMAL Or They are normal FEMALES HAVE TWO X CHROMOSOMES DEFECTIVE NORMAL DEFECTIVE Females have one normal gene that works. need 2 Females __________ defective recessive alleles to show the disorder X-LINKED RECESSIVE Examples of ________________________ DISORDERS: HEMOPHILIA ____________________ COLORBLINDNESS ____________________ DUCHENNE MUSCULAR DYSTROPHY ____________________ HEMOPHILIA CAUSE: Mutation in genes for __________________ Blood clotting proteins on X chromosome carried ______ Blood clotting proteins are missing so person with this disorder can’t stop bleeding when bleed to death from minor injured; can ________________ cuts or suffer internal bleeding from bruises or bumps. HEMOPHILIA Treatment: injections of normal clotting Need ____________ proteins to stop bleeding More common in ______ males because it is _____________ TWO recessive X-linked, but females with ______ hemophilia alleles will also show the trait. 1 in 10,000 males has hemophilia COLORBLINDNESS CAUSE: Mutation in one of three genes for _______________ carried on X chromosome Color vision Persons with this disorder have trouble distinguishing colors. Red-green _________________ colorblindness is most common Seen in 1 in 10 males 1 in 100 females http://gizmodo.com/gadgets/peripherals/samsung-develops-lcd-for-colorblind-036306.php Duchenne Muscular Dystrophy CAUSE: deletion in gene that codes for a muscle protein _______________ Results in progressive weakening ____________________ and loss of skeletal muscle ___________________ http://www.cadenhead.org/workbench/gems/jerry-lewis-telethon.jpg http://www.tokyo-med.ac.jp/genet/chm/dei.gif Duchenne Muscular Dystrophy (DMD) SYMPTOMS: 1 in 3000 male births Appears before age 5 Progressive muscle weakening Most in wheelchair by age 13 Eventually lethal Play What’s the pattern: Y-linked traits show up _______ ONLY in _______ males ________ X-linked recessive traits: __________________ ______________________ more common in males than females. ________________ ONLY FEMALES can be ________. carriers AUTOSOMAL RECESSIVE traits: _______________________ FEMALES can be ________ carriers BOTH MALES ______ & _________ CHROMOSOMAL Abnormalities ________________ • 1 infant in 200 newborns has a chromosomal abnormality • 28% of first trimester miscarriages have a chromosomal abnormality • Abnormalities in larger chromosomes don’t usually survive CHROMOSOMAL MUTATIONS ____________________________: structure or Change in the ______________ number ____________ of chromosomes Homologous chromosomes fail to separate during MEIOSIS ________________ NONDISJUNCTION = _________________________ One cell gets 2 copies of the chromosome the other cell gets none. Normal Meiosis Nondisjunction http://web.udl.es/usuaris/e4650869/docencia/gen_etica/meioferti2.html http://www.tokyo-med.ac.jp/genet/anm/domov.gif Nondisjunction Nondisjunction Since it happens to a sperm or egg, the new baby can end up 3 copies with _____________ of a chromosome TRISOMY = __________________ OR one copy of a only ___________ chromosome = ___________________ MONOSOMY Human Abnormalities caused by Non-Disjunction __________________ Down syndrome Klinefelter syndrome __________________ Turner syndrome __________________ TRISOMY 21 Down syndrome (= ____________) Down syndrome (Trisomy 21) • 1 in 800 births • Similar facial features • Slanted eyes • Protruding tongue Down syndrome (Trisomy 21) Simian line on palm Down syndrome (Trisomy 21) • Most common chromosomal abnormality • 50% have heart defects that need surgery to repair • Mild to severe mental retardation • Increases susceptibility to many diseases • Risk of having a child with Down syndrome increases with age of mom Down syndrome (Trisomy 21) • Risk of having a child with Down syndrome related to age of mom • More common in women UNDER 16 or OVER 35 Cells that make eggs start meiosis in embryo Stop in PROPHASE I (synapsis) One egg restarts & finishs division each month So an egg released at age 40 has been in synapsis for 40 years . . . chromosomes more likely to “stick” Turner syndrome XO Turner syndrome ____ • • • • • • • • • 1 in 5000 births Females have only one X chromosome Small size Slightly decreased intelligence 35% have heart abnormalities Hearing loss common Broad chest Reproductive organs don’t develop at puberty Can’t have children http://medgen.genetics.utah.edu/photographs/diseases/high/611.gif Klinefelter syndrome XXy Klinefelter syndrome • 1 in 1000 births • Males have extra X chromosomes (Can be XXy, XXXy, or XXXXy) • Average to slight decrease in intelligence • Small testes/can’t have children • Usually not discovered until puberty when don’t mature like peers X-chromosome Inactivation ONE X chromosome In female cells ______ SWITCHED OFF is randomly ________________ It condenses and forms a dense region in the nucleus called a BARR BODY _____________ http://fig.cox.miami.edu/~cmallery/150/gene/barr.htm CAT COLOR http://www.islandstrolling.com/mainland/peloponnes/photo/mystra_cat_white_orange_black.jpg In cats, a gene that controls the SPOT COLOR _____________ is carried on the X chromosome ____________________ In some female cells the X with the allele for orange spots is switched off and in some cells the X with the allele for black spots is switched off, so cat has different colored spots. See a video CAT COLOR http://ascensionparish.net/forum/messages/14/2493.jpg Male cats have only _________ one X chromosome, so they can only have ____________ one color of spots! THINK ABOUT IT? How many colors of spots could a male cat with Klinefelter syndrome have?